The present invention relates to a method for controlling a wall saw system when making a separating cut.
A method is known from EP 1 693 173 B1 for controlling a wall saw system when making a separating cut in a workpiece between a first end point and a second end point. The wall saw system comprises a guide track and a wall saw with a saw head, a motorized feed unit that displaces the saw head parallel to a feed direction along the guide track, and at least one saw blade that is attached to a saw arm of the saw head and is driven about a rotation axis by a drive motor. The saw arm is pivotably designed by means of a pivot motor and a pivot axis. By means of a pivot motion of the saw about the swivel axis, the penetration depth of the saw blade into the workpiece is changed. The motorized feed unit comprises a guide carriage and a feed motor, wherein the saw is attached to the guide carriage and is displaced via the feed motor along the guide track. To monitor the wall saw system, there is provided a sensor device with a pivot angle sensor and a displacement sensor. The pivot angle sensor measures the current pivot angle of the saw arm and the displacement sensor measures the current position of the saw head on the guide track. The measured values for the current pivot angle of the saw arm and the current position of the saw head are transmitted on a regular basis to a control unit of the wall saw.
The known method for controlling a wall saw system is subdivided into a preparatory part and a control unit-controlled processing of the separating cut. In the preparatory part, the user determines at least the saw blade diameter of the saw blade, the positions of the first and second end points in the feed direction, and the end depth of the separating cut; additional parameters may be the material of the workpiece to be worked on and the dimensions of the embedded rebar. From the input parameters, the control unit determines for the separating cut a suitable main cutting sequence of main cuts, wherein the main cutting sequence comprises at least a first main cut having a first main cutting angle of the saw arm and a first diameter of the utilized saw blade, as well as a subsequent second main cut having a second main cutting angle of the saw arm and a first diameter of the utilized saw blade.
The known method for controlling a wall saw system has the disadvantage that for cutting hard materials, no special method is provided for controlling the wall saw. When cutting hard materials, polishing of the cutting segments can occur during the pivot motion of the saw blade in the workpiece. The polishing of the cutting segments reduces the service life of the cutting segments and the cutting speed of the saw blade.
The object of the present invention consists in developing a method for controlling a wall saw system, which allows for the cutting of hard materials and in which the service life and the cutting speed of the saw blade are optimized.
In the method for controlling a wall saw system referred to in the beginning, this task is achieved according to the invention by the features of the independent claim. Advantageous developments are indicated in the dependent claims.
According to the invention, it is provided that the pivot motion of the saw arm out of the first main cutting angle into a new pivot angle is performed in at least two steps with at least one intermediate angle, wherein between the pivot motions of the saw arm into the intermediate angles, a free-cutting of the saw blade occurs in each case.
Saw blades for wall saws are constructed in a two-part manner out of a base body and cutting segments on the perimeter of the base body. The cutting segments consist of a matrix material, in which diamond particles are embedded. To expose the diamond particles during cutting, a minimum surface pressure is required. If the surface pressure falls below the minimum surface pressure, the diamond particles are not exposed during cutting with the saw blade and there is the risk that a polishing of the cutting segments occurs, which reduces the service life of the cutting segments and the cutting speed of the sawblade. The minimum surface pressure of the cutting segments corresponds to a critical arc length of the saw blade, which may not be exceeded. The value of the critical arc length of a saw blade depends on multiple parameters, including the specification of the saw blade, the material of the workpiece to be cut, as well as the power and torque of the drive motor for the saw blade.
The breakdown of the pivot motion into at least two steps reduces the risk that a polishing of the saw blade occurs. A smaller pivot angle results in reducing the arc length of the saw blade, which is engaged with the workpiece, or the number of the cutting segments, which are engaged with the workpiece. The free-cutting of the saw blade, which occurs between the pivot motions of the saw arm, results in the arc length of the saw blade, engaged with the workpiece, being further reduced.
Preferably, the pivot motion of the saw arm out of the first main cutting angle into the new pivot angle is performed in n steps with n−1 intermediate angles, wherein between the pivot motions of the saw arm into the intermediate angles, a free-cutting of the saw blade occurs. The number of steps depends among other things on the specification of the saw blade, the hardness of the material, as well as the power and torque of the drive motor for the saw blade. The intermediate angles can be established by the operator or the intermediate angles can be established by the control unit of the wall saw system as a function of various boundary conditions. For the method according to the invention, the intermediate angles represent an input variable that is used to control the wall saw.
Preferably, prior to starting the processing controlled by the control unit, a saw arm length of the saw arm, which is defined as the distance between the pivot axis of the saw arm and the rotation axis of the saw blade, and a distance between the pivot axis and the top side of the workpiece are defined. For the controlled processing of a separating cut, various parameters must be known to the control unit. These include the saw arm length that represents a fixed, device-specific dimension of the wall saw, and the perpendicular distance between the pivot axis and the surface of the workpiece that depends on, besides the geometry of the wall saw, the geometry of the guide track used as well.
In a particularly preferred manner, prior to starting the controlled processing, a first width for a blade guard used in the first main cut and a second width for a blade guard used in the second main cut are established, wherein the first and second widths respectively are composed of a first distance of the rotation axis to the first blade guard edge and a second distance of the rotation axis to the second blade guard edge. When an end point represents an obstacle, the position controlling of the saw head occurs via the blade guard edge, facing the obstacle, of the utilized blade guard. For an asymmetrical blade guard, the first and second distances of the rotation axis to the blade guard edges are different, whereas for a symmetrical blade guard, the first and second distances of the blade guard edges coincide with half the width of the blade guard.
In a first preferred embodiment of the method according to the invention, the pivot motion occurs from the first main cutting angle into the new main cutting angle at the first end point and the saw head is positioned in the jth cut, j=1 to n−1, in such a manner that after the pivot motion of the saw arm in the jth intermediate angle, a first boundary, facing the first end point, of the wall saw coincides with the first end point, wherein the first boundary of the wall saw is formed by a first upper exit point, facing the first end point, of the utilized saw blade on the top side of the workpiece when the first end point represents a free end point without an obstacle, by a first saw blade edge, facing the first end point, of the utilized saw blade when the first end point represents an obstacle and processing occurs without a blade guard, and by a first blade guard, facing the first end point, of the utilized blade guard when the first end point represents an obstacle and processing occurs with a blade guard.
Every step comprises the method steps of positioning the saw head, pivoting the saw arm into the intermediate angle, and moving the saw head for free-cutting of the saw blade. After the pivot motion of the saw arm into the intermediate angle, the first boundary coincides with the first end point. For a free end point without an obstacle, position controlling occurs via the first upper exit point of the saw blade on the top side of the workpiece. When the first end point represents an obstacle, the first saw blade edge (cutting without a blade guard) or the first blade guard edge (cutting with a blade guard) are utilized for position controlling.
After the pivot motion of the saw arm into the jth intermediate angle, where j=1 to n−1, the first upper exit point coincides with the first end point when the pivot axis has a distance to the first end point of √[h(±ß1,j)·(D−h(±ß1,j))]−δ·sin(±ß1,j), wherein h(±ß1,j)=D/2−Δ−δ·cos(±ß1,j) refers to the penetration depth of the utilized saw blade into the workpiece for the jth intermediate angle, the first saw blade edge of the utilized saw blade coincides with the first end point when the pivot axis has a distance to the first end point of D/2−δ·sin(±ß1,j), and the first blade guard edge of the utilized blade guard coincides with the first end point when the pivot axis has a distance to the first end point of B2a−δ·sin(±ß1,j).
After the pivot motion, the saw arm in the jth step, j=1 to n−1, with the saw arm tilted at the jth intermediate angle, is moved by a displacement distance of √[h2·(D−h2)]−δ·sin(±α2), wherein h2=h(±α2, D)=D/2−Δ−δ·cos(±α2) refers to the penetration depth of the utilized saw blade into the workpiece for the second main cutting angle. By means of the feed motion of the saw head, the saw blade is cut free, and the part of the saw blade engaged with the workpiece is reduced.
After the n−1th step, the saw head is positioned in such a manner that after the pivot motion of the saw arm into the new main cutting angle, the first boundary, facing the first end point, of the wall saw coincides with the first end point. After the pivot motion of the saw arm into the second main cutting angle, the first upper exit point coincides with the first end point when the pivot axis has a distance to the first end point of √[h2·(D−h2)]−δ·sin(±α2), wherein h(±α2)=D/2−Δ−δ·cos(±α2) refers to the penetration depth of the utilized saw blade into the workpiece at the second main cutting angle with the second diameter, the first saw blade edge of the utilized saw blade coincides with the first end point when the pivot axis has a distance to the first end point of D/2−δ·sin(±α2), and the first blade guard edge of the utilized blade guard coincides with the first end point when the pivot axis has a distance to the first end point of Ba−δ·sin(±α2).
In a second preferred embodiment of the method according to the invention, the pivot motion occurs from a first main cutting angle into the new main cutting angle at the second end point and the saw head is positioned in the jth intermediate cut, j=1 to n−1, in such a manner that after the pivot motion of the saw arm into the jth intermediate angle, a second boundary, facing the second end point, of the wall saw coincides with the second end point, wherein the second boundary of the wall saw is formed by a second upper exit point, facing the second end point, of the utilized saw blade on the top side of the workpiece when the second end point represents a free end point without an obstacle, by a second saw blade edge, facing the second end point, of the utilized saw blade when the second end point represents an obstacle and processing occurs without a blade guard, and by a second blade guard edge, facing the second end point, of the utilized blade guard when the second end point represents an obstacle and processing occurs with a blade guard.
Every step comprises the method steps of positioning the saw head, pivoting the saw arm into the intermediate angle, and moving the saw head for the free-cutting of the saw blade.
After the pivot motion of the saw arm into the jth intermediate angle, where j=1 to n−1, the second upper exit point coincides with the second end point when the pivot axis has a distance to the second end point of √[h(±ß2,j)·(D−h(±ß2,j))]+δ·sin(±ß2,j), wherein h(±2,j)=D/2−Δ−δ·cos(±ß2,j) refers to the penetration depth of the utilized saw blade into the workpiece for the jth intermediate angle, the second saw blade edge of the utilize saw blade coincides with the second end point when the pivot axis has a distance to the second end point of D/2+δ·sin(±ß2,j), and the second blade guard edge of the utilized blade guard coincides with the second end point when the pivot axis has a distance to the first end point of Bb+δ·sin(±ß2,j).
After the pivot motion, the saw head in the jth step, j=1 to n−1, with the saw arm tilted at the jth intermediate angle, is moved by a displacement distance of √[h2·(D−h2)]−δ·sin(±α2), wherein h2=h(±α2, D)=D/2−Δ−δ·cos(±α2) refers to the penetration depth of the utilized saw blade into the workpiece for the second main cutting angle. By means of the feed motion of the saw head, the saw blade is cut free and the part of the saw blade engaged with the workpiece is reduced.
After the n−1th step, the saw head is positioned in such a way that after the pivot motion of the saw arm into the new main cutting angle, the second boundary, facing the second end point, of the wall coincides with the second end point.
After the pivot motion of the saw arm into the second main cutting angle, the second upper exit point coincides with the second end point when the pivot axis has a distance to the second end point of √[h2·(D−h2)]+δ·sin(±α2), wherein h(±α2)=D/2−Δ−δ·cos(±α2) refers to the penetration depth of the utilized saw blade into the workpiece for the second main cutting angle, the second saw blade edge of the utilized saw blade coincides with the second end point when the pivot axis has a distance to the second end point of D/2+δ·sin(±α2), and the second blade guard edge of the utilized blade guard coincides with the second end point when the pivot axis has a distance to the second end point of Bb+δ·sin(±α2).
The first and second main cuts are performed with a saw blade and a blade guard. Alternatively, the first main cut is performed by a first saw blade having a first saw blade diameter and a first blade guard having a first blade guard width, and the second main cut is performed by a second saw blade having a second saw blade diameter and a second blade guard having a second blade guard width.
Embodiments of the invention are described hereafter by means of drawings. These are not necessarily meant to depict the embodiments true to scale; rather, the drawings, where useful for explanation purposes, is executed in a schematic and/or slightly distorted form. In regard to supplements of the teachings directly evident from the drawings, one shall refer to the relevant prior art. In doing so, one shall take into account that diverse modifications and changes pertaining to the form and detail of an embodiment may be undertaken without deviating from the general idea of the invention. The features of the invention disclosed in the description, drawings, and claims may be significant individually as well as in any combination for developing the invention. In addition, falling within the scope of the invention are all combinations of at least two features disclosed in the description, drawings, and/or claims. The general idea of the invention is not restricted to the exact form or detail of the preferred embodiments shown and described below or limited to a subject matter that would be restricted in comparison to the subject matter claimed in the claims. For given dimensional ranges, values lying within the mentioned limits shall be disclosed as limits and they can be implemented and claimed as desired. For simplicity's sake, the same reference signs are used below for identical or similar parts or parts with identical or similar functions.